Design Of Wide Load High Efficiency Buck Converter Based On Current Mode Control

With the progress of the times,the development of science and technology is getting faster and faster,more and more electronic products have entered our field of vision,and people are more and more consuming and using portable electronic products.With the continuous increase in the types of consumer electronic products,the requirements for power management chips are also getting higher and higher.Buck converters have good characteristics in applications with a wide load range,and have high energy conversion efficiency.Widely used in electronic products.The control method of peak current mode has better comprehensive performance,this thesis adopts the control method of peak current mode.The loop modeling of the system is carried out by the description function method,and the frequency compensation parameters are designed to satisfy the loop stability of the system under a wide load range.Use an external power tube to make the system have enough load capacity.Under light load,a light load control method is designed to improve the energy conversion efficiency of the system.A low-dropout linear regulator with fast transient response is designed to power the system internally,and its power rails can be switched to improve energy conversion efficiency.An error amplifier with higher gain is designed to ensure the output accuracy of the system,and the error amplifier has a clamping function,which directly sets the current limit for the inductor current.Using a current comparator as a PWM comparator reduces the number of system signal nodes and makes the loop response faster.In order to prevent the reverse flow of the inductor current,a reverse current comparator is designed to improve the energy conversion efficiency of the system.In this thesis,the 0.18μm BCD process is used,and simulation software is used to design and simulate the LDO,error amplifier,PWM current comparator and light-load comparator.Finally,the transient response of Buck converter in various extreme applications is carried out.The system is also simulated in light load mode and efficiency is calculated.The simulation results show that the chip can work in the input voltage range of 4.5～30V,the output voltage range is 1V～12V,and the load current range is up to20 A.In the entire load range,the system has a high energy conversion efficiency,and under a light load of 100 m A,it also has an efficiency of more than 90%.